The present invention refers to a dishwashing machine provided with improved electric means for heating up the working medium.
Traditionally, dishwashing machines have been known to include an electric resistance-type heating element for heating the water to be sprayed onto the washload items and possibly also heating the air to dry the same washload items at the end of the wash cycle.
In traditional solutions, as described for instance in the Italian Utility Model Application No. 34093 B/90 filed on Dec. 13, 1990, the heating element is of the sheathed type for submerged applications and is arranged in the washing tank of the machine, in correspondence of the bottom of said tank. The heating element is wetted by the water and flooded by the water which, after having been sprayed onto the washload items, falls back by gravity onto the bottom of the tank.
In all such solutions, the heat exchange effect between the heating element itself and the wash water is not ideal.
Furthermore, since the heating element is substantially exposed inside the wash tank, it undesirably produces bad odors and can be undesirably hot to a user who opens the door of the dishwashing machine as soon as the final hot-air drying phase is terminated.
In view of substantially eliminating such drawbacks, dishwashing machines have therefore been proposed that make use of so-called "ducted" heating elements, described for instance in U.S. Pat. No. 2,914,935. In such dishwashing machines, the heating element is housed in a hermetically sealed casing which is a part of the water recirculation circuit and is arranged outside the washing tank. As a result, "ducted" heating elements are difficult to access for maintenance or replacement purposes and, in any case, are not able to perform conventional final hot-air drying of the washload items. To be able to perform a final hot-air drying of the washload items to any effective extent, these dishwashing machines must be provided with special condenser-type, or ventilation type, drying arrangements, which considerably and undesirably add to the complexity of the overall construction of the dishwashing machine.